Question: $\dfrac{8}{4} - \dfrac{7}{8} = {?}$
$ = {\dfrac{8 \times 2}{4 \times 2}} - {\dfrac{7 \times 1}{8 \times 1}} $ $ = {\dfrac{16}{8}} - {\dfrac{7}{8}} $ $ = \dfrac{{16} - {7}}{8} $ $ = \dfrac{9}{8}$